Wdr64, a Testis-Specific Protein, is Involved in the Manchette and Flagellum Formation by Interacting with Odf1

WD40 repeat (WDR) domain is present in a wide range of proteins, providing sites for protein-protein interactions. Recent studies showed that WDR proteins played an indispensable role in spermatogenesis, such as spermatocyte division, sperm head formation and flagella assembly. In this study, we identified a novel testis-specifically expressed gene, WDR64, which has the typical characteristics of WD40 proteins with two β-propellers, and was highly conserved in mammalia. The cellular expression of WDR64 was evaluated in published single-cell mRNA datasets, demonstrating that WDR64 was specifically expressed in male germ cells, especially in the postmeiotic germ cells. During spermiogenesis in mice, Wdr64 was localized posterior to the nucleus in steps 8-14 spermatids in line with the dynamic localization of manchette, moved to the flagella in steps 15-16 spermatids, and localized at the midpiece of the flagellum in mature spermatozoa. To explore the function of WDR64, we performed immunoprecipitation-mass spectrometry (IP-MS) to screen its interacting proteins, and found that WDR64 interacted with ODF1 to form a complex. The Wdr64/Odf1 complex located at the manchette during nucleus shaping and finally at the midpiece of mature spermatozoa tail, suggesting that it may be involved in the assembly of manchette and flagella during spermiogenesis. Our findings provide the first understanding for the characteristic of WDR64 and its molecular mechanism in spermiogenesis.